The present invention relates to front-end separation of separate fractions of municipal solid waste (MSW) and more particularly, in one aspect, to an improved assembly for splitting open bags bearing MSW fractions such as, grass, leaves, yard waste, and the like; and, in another aspect, for splitting open bags bearing cans, bottles, and the like, e.g., so-called "blue bags". "Blue bags" refers to bags (the color blue relating to the bag color used in the original curbside recycling programs, though bags of any color can be used) that contain separated recyclables, e.g., paper, newsprint, plastics, aluminum cans, plastic bottles, or the like.
Solid waste materials of the type typified by MSW traditionally have presented problems of disposal. These disposal difficulties have become increasingly critical as populations have expanded and as the per capita production of solid waste has increased. In addition to using waste as a source of fuel or compost, industrial and home refuse or MSW typically comprises several components or fractions which are worth reclaiming. In particular, glass, ferrous and non-ferrous metals, plastic, and paper components are sufficiently valuable to justify their separation from composite MSW. Conventionally, such solid waste has been disposed of by incineration and/or landfill. With the present concern over problems associated with the protection of the environment and because of scarcity of landfill space and governmental regulations, both of these traditional techniques of disposal have become undesirable. Further, separation systems, to remain efficient, must be capable of having a reasonably high throughput rate for the material processed and since MSW varies from one area to the next, and between collections, the separation system also must be capable of handling materials which vary widely in nature and composition. To the present, the throughput rates of conventional systems have not been adequately high enough to derive efficiencies permitting the use of equipment in municipalities of small or medium size. However, because of the ever-increasing rigid requirements for carrying out waste treatment and because of the increasing scarcity of landfill space, some technique must be found to effectively increase such output rates.
To achieve the efficient separation of more valuable fractions of MSW and to derive an environmentally safe marketable compost or refuse derived fuel product, a waste treatment process should be carried out wherein raw MSW is passed through a variety of reduction, separation, and related treatment stages. These stages serve to remove inorganic components such as metals, glass, and plastics from the organic component of the MSW. The segregated or separated by-product materials, such as ferrous and non-ferrous metals, glass, and plastic, increasingly are becoming valuable resources worthy of the expenditure of capital for effective separation equipment. Of course, the quality and resultant value of the organic material also is dependent upon the corresponding quality of separation, the presence of plastics, glass, or other foreign particles being undesirable or unacceptable for most commercial applications.
A broad variety of separation techniques have been known to industry. Among those, both manual and automatic techniques have been used. The manual technique that generally involves human pickers usually is not cost effective nor desirable. The automatic techniques which rely on the fraction size for sorting by a grizzly or the magnetic characteristics of the magnetic fraction or the density of other fractions for air separation generally have not been employed by industry in such a manner as to eliminate the extensive need of human pickers to further separate MSW into the various fractions where air separation techniques have been applied to municipal waste separation. Designers have found that achieving high quality separation within reasonable cost limits proves to be an elusive goal. Since MSW varies widely in geographical, as well as daily, make-up and consistency, a uniform product is not available for separation treatment. Therefore, any separation system involving the sorting of solid waste must be capable of handling a wide variation of waste components.
An improved bag splitting assembly is disclosed in commonly-assigned U.S. Pat. No. 5,267,823. This assembly finds good use in the solid waste sorting system disclosed in commonly-assigned U.S. Pat. No. 5,101,977. A preferred conveyor system for use in both the bag splitting assembly and the solid waste sorting system is disclosed in commonly-assigned U.S. Pat. No. 5,219,064. The disclosure of these patents is expressly incorporated herein by reference.
In particular, most home owners and businesses bag their grass clippings, leaves, tree branches, bush clippings, flowers and flower stalks, vegetable refuse, and similar compostable yard waste (hereinafter, collectively "yard waste") in plastic bags and place such bagged yard waste for collection with their other refuse and garbage. The same is true in many communities where "curbside recycling" is practiced, i.e., separately bagging paper, newsprint, plastics, aluminum cans, etc. for recycling. Since such yard waste and some recyclables can be composted (as many home gardeners already practice) and/or other recyclables recycled for reuse, it would be beneficial to develop an automatic system that would free the yard waste, recyclables, and the like, from the plastic bags for processing of such yard waste. The same is true for the cans and bottles fraction that is segregated in separate plastic bags by curbside recycling efforts.